Babnecl Auto Headliner Fabric 38" L × 60" W Mesh Type with Foam Backing - Tube Packaging - Gray Interior Replacement Material for Car/Truck/SUV/RV Roof - Home Repair/DIY Headliner Material

Looks like it fabric covered thin foam, called headliner as its commonly used for headlining the inside of a car roof. https://www.amazon.com/Babnecl-Auto-Headliner-Fabric-Backing/dp/B0DCKFG99L/ref=sr_1_16 Maybe : https://www.wawak.com/bag-making/bag-interfacing/bosal-in-r-foam-plus-fusible-non-woven-interfacing-58-x-1-yd/#sku=intf309 https://www.wawak.com/bag-making/bag-interfacing/pellon-ff79f-flex-foam-two-sided-fusible-polyester-interfacing-20-x-60-white/#sku=intf564